Author Topic: m42 timing problems  (Read 4581 times)

jrobie79

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m42 timing problems
« on: June 02, 2013, 07:50:58 PM »
so I changed my head gasket, put everything together, had the cams locked in place and the cam gears zip tied to the chain, so I figured everything was ok for reassembly.

I go to start it up and this is what it sounded like:

http://www.youtube.com/watch?v=sm6UsHF6yYo&

I knew this wasn't right so I shut it off did some basic reaserch and figured it was the timing. So I took the valve cover off again. There are 15 "dots" between the two arrows on the cam gears. I used the dowel in the flywheel to lock it at TDC cylinder 1, however the square ends of the cams aren't in the same plane when its locked TDC, see below:









How would I go about fixing this?

jmsra

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Re: m42 timing problems
« Reply #1 on: June 02, 2013, 08:32:34 PM »
I would loosen up the cam gear bolts and straighten up the cams on the back side with a couple of adjustable wrenches. Once you have the cams straight, check to see what it's gonna take for the cam gears to have the arrows pointing straight up. My guess is your going to be off exactly one tooth on one or the other. I had the exact same "diesel" problem and had to adjust the exhaust cam by one tooth. Just remember the cam bolts should be in the middle of the slots when everything is lined up correctly. Good Luck!

wazzu70

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Re: m42 timing problems
« Reply #2 on: June 03, 2013, 04:55:44 PM »
I would loosen up the cam gear bolts and straighten up the cams on the back side with a couple of adjustable wrenches. Once you have the cams straight, check to see what it's gonna take for the cam gears to have the arrows pointing straight up. My guess is your going to be off exactly one tooth on one or the other. I had the exact same "diesel" problem and had to adjust the exhaust cam by one tooth. Just remember the cam bolts should be in the middle of the slots when everything is lined up correctly. Good Luck!

Excellent advice! Thats exactly what I was going to say, so I will just second it.
-Nick
91 E30 M42 with VEMS

DesktopDave

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Re: m42 timing problems
« Reply #3 on: June 03, 2013, 08:25:34 PM »
+2 on that, hopefully it'll be an easy fix.

Also don't forget that the cam timing might be ever-so-slightly-off if the head has been resurfaced, or if the head gasket is not OEM spec.  BMW and other companies make different thickness HGs to compensate for turbos, skimming the head, etc.
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jmsra

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Re: m42 timing problems
« Reply #4 on: June 03, 2013, 10:44:48 PM »
Thanks guys. I'm just glad to be able to finally return some of the good advice I've received on this great forum and hopefully help someone else!

jrobie79

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Re: m42 timing problems
« Reply #5 on: June 04, 2013, 08:20:07 AM »
so I got the ends pretty damn parallel to each other and the bolts actually were int he middle of the holes, the chain wasn't off or anything, just a combination of the two being out of whack I guess. Then realized I massacred my upper timing case and thermostat housing gaskets so I just put some "right stuff" RTV and started it up. No more dieseling, however I did get code 1215 which makes me think that gasket RTV possibly wasnt sealing 100%. Going to start it up tonight and see what happens, if I get the same vacuum leak symptons looks like I'll order some new gaskets.

jrobie79

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Re: m42 timing problems
« Reply #6 on: June 05, 2013, 09:46:07 AM »
got everything aligned...noise went away. However, I still have FU**ING white smoke coming out the back. It's only filled with water right now as I was going to flush the cooling system, but the white smoke is still there. Also when I drive at WOT it stumbles and hesitates.

I took the head from my sisters car,  because my original was a little nicked up, and hers just looked better which had no white smoke. However, I do remember driving her car and it did have the WOT issue. Could this be a bent valve? Also since the white smoke is still coming out, possibly my block is cracked?

Seems like two problems on this one. Any suggestions?

jmsra

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Re: m42 timing problems
« Reply #7 on: June 05, 2013, 02:23:56 PM »
That does sound like two separate problems. 1) WOT issue - If you have access to a compression test kit, i would check that to confirm valve sealing. 2) White smoke - possible head gasket or cracked head. maybe try using a combustion leak tester to confirm exhaust in the coolant. I think your head would be cracked before your block.
Worst case, you may have to take both of your heads to a machine shop to make one good one.

jrobie79

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Re: m42 timing problems
« Reply #8 on: June 05, 2013, 03:26:09 PM »
where can I get this combustion leak tester

jmsra

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Re: m42 timing problems
« Reply #9 on: June 05, 2013, 08:33:12 PM »
Amazon seems to have the cheapest one, but i also see WalMart carries them.
http://www.amazon.com/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76

jrobie79

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Re: m42 timing problems
« Reply #10 on: June 06, 2013, 09:09:16 AM »
compression came back all right around 185-195-200 ish. I think I'm just gonna throw a known working m42 in there, then do my S5x swap sometime this winter.